The present invention relates generally to radio display pagers, and more specifically to a radio display pager capable of displaying callers' messages.
According to conventional radio display paging systems, a destination pager's identifier, or telephone number, is dialed to the public switched telephone network (PSTN) to access a voice response unit 30 of a paging system (FIG. 1). The voice response unit urges the caller to send either his or her own telephone number or a message. If the caller's telephone number is to be displayed, it is dialed by the caller and the dialed information is passed through a selector 31 to a store and forward circuit 32 in which it is stored. The store and forward circuit 32 receives the pager's identifier from the PSTN and forwards the dialed information and the received pager's identifier to a transmitter 33 in which it is converted to a specified line code, which is broadcast from antenna 35. On receiving the transmitted signal, the pager checks to determine if the pager identifier contained in the signal matches the pager's individual identifier, and if it does, the pager displays the caller's telephone number. If the caller's message is to be displayed, on the other hand, the caller dials two symbol marks (asterisks) in sequence and then a sequence of sentence codes signifying letters and numerals. The selector analyzes the two asterisks and knows that the dialed codes following the asterisks comprise a message, and passes the dialed information to a store, convert and forward circuit 34 in which the two asterisks are converted to other symbols ("--"). On receiving the pager's identifier from the PSTN, the circuit 34 applies the pager's identifier, the converted symbols ("--") and the message to the transmitter. On receiving this signal, the pager knows that the codes following the symbols "--" are a message and uses them as an address pointer for accessing a memory in which sentence patterns and alphanumeric data are stored.
However, users of this type of paging system are required to additionally dial special symbols when calling in a message display mode and the paging system is required to distinguish the message display mode from other display modes.